From the Guidelines
A neonate born to a mother with Graves' disease should undergo thyroid function tests within the first 24-48 hours of life. This initial screening should include measurement of TSH (thyroid-stimulating hormone) and free T4 levels 1. The American College of Obstetricians and Gynecologists (ACOG) recommends that the newborn's physician be aware of the mother's Graves' disease due to the associated risk of neonatal thyroid dysfunction 1.
Importance of Early Screening
Follow-up testing may be necessary at 7-10 days of life, and again at 2-4 weeks, particularly if the initial results are abnormal or if the infant shows any signs of thyroid dysfunction. This monitoring is crucial because maternal thyroid-stimulating immunoglobulins (TSI) can cross the placenta and affect the baby's thyroid function, potentially causing neonatal hyperthyroidism 1.
Signs and Symptoms of Neonatal Hyperthyroidism
While some babies may appear normal at birth, symptoms can develop within the first week as maternal antithyroid medications clear from the infant's system. Signs of neonatal hyperthyroidism include:
- Irritability
- Poor weight gain despite good feeding
- Tachycardia
- Exophthalmos Early detection and treatment can prevent serious complications such as heart failure, developmental issues, and craniosynostosis.
Treatment and Management
Treatment with methimazole may be necessary for neonates with hyperthyroidism, with a starting dose of 0.5-1 mg/kg/day divided every 8 hours. However, the provided evidence does not specify the exact treatment protocol for neonatal hyperthyroidism. Therefore, it is essential to consult with a pediatric endocrinologist for guidance on treatment and management.
Key Considerations
- Maternal thyroid-stimulating immunoglobulins (TSI) can cross the placenta and affect the baby's thyroid function 1.
- Neonatal thyroid dysfunction is a concern in babies born to mothers with Graves' disease 1.
- Early detection and treatment of neonatal hyperthyroidism can prevent serious complications.
From the Research
Thyroid Function Tests in Neonates Born to Mothers with Graves' Disease
- Neonates born to mothers with Graves' disease are at risk for significant morbidity and mortality and need to be appropriately identified and managed 2
- The initial risk assessment should be based on maternal thyroid stimulating hormone (TSH) receptor antibodies, and if levels are positive, the newborn should be regarded as "at risk" for the development of hyperthyroidism 2
- Measurement of cord TSH and fT4 levels is not indicated, but fT4 and TSH levels should be performed at day 3 to 5 of life, repeated at day 10 to 14 of life, and followed clinically until 2 to 3 months of life 2
Predictive Factors for Neonatal Hyperthyroidism
- FT4 elevation between days 3 and 7 but not at birth is predictive of the development of hyperthyroidism 3
- TRAb status should be checked in the third trimester in mothers with Graves' disease and on cord blood in their neonates; if positive, it indicates a high risk of neonatal hyperthyroidism 3
- The daily ATD dose in the third trimester is the strongest predictor of neonatal hypothyroidism at delivery, with cutoff doses of 10 mg/day for methimazole and 150 mg/day for propylthiouracil 4
Long-term Outcomes of Children Born to Mothers with Graves' Disease
- Thyroid dysfunction in infants born to mothers with Graves' disease can affect growth and development later in life 5
- Children born to mothers with Graves' disease should have careful evaluation of thyroid function tests and long-term follow-up, as some may have abnormal growth and development 5
- Infants of mothers with Graves' disease may develop central hypothyroidism or primary hypothyroidism, and serial monitoring of thyroid function tests is necessary, even if the initial screening is normal 6